1. Field of the Invention
The present invention relates to fluid pumps and more particularly to such a pump having an integral check valve employing a self-biasing spring means for yieldably moving a closure member to seal a fluid orifice.
2. Brief Description of the Prior Art
In the past, it has been the conventional practice to provide the body of a fluid pump with a gland or cavity having an inlet and an outlet with a closure means yieldable to open and close one of the orifices or ports. Such valves are normally identified as check valves for the control of fluid flow between the inlet and outlet orifices. Passive check valves are defined as those valves which have a movable element that is able to seal against an orifice. The movable element can be free to move against or away from the orifice or it may be spring-loaded against the orifice for biased closure. In the latter instance, a preselected fluid pressure may be required to unseat the movable element against the bias of a spring member in order to establish flow. The spring-loading ensures that fluid will not leak back into the pump's output orifice or port.
Conventional springs incorporating metal leaf springs, helical coils or the like have been used to place a bias on the movable member to effect yieldable sealing. These spring closures for check valves are usually expensive and require extensive assembly procedures during the construction of the fluid pump. Also, the spring member is not necessarily integral with the check valve so that added parts are required in conventional assemblages.
Therefore, a long-standing need has existed to provide a novel integral fluid pump and check valve combination in a unitary structure which is inexpensive compared with conventional metal springs and that can be cut to a desired shape. Preferably, the spring should be self-biased and act as a filter media.